Pre-plated reactive diffusion-bonded battery electrode plaques

Abstract

A high strength, metallic fiber battery plaque is made using reactive diffusion bonding techniques, where a substantial amount of the fibers are bonded together by an iron-nickel alloy.

I claim: 
     
       1. A method of producing a high strength, metallic, electrically conductive plaque comprising the steps of: (1) providing a layer of iron fibers,   (2) nickel coating said iron fibers, and   (3) after nickel coating, heating the nickel coated iron fibers to form an iron-nickel alloy bond between a substantial amount of the fibers.   
     
     
       2. The method of claim 1, where the fibers are heated at a temperature of about 800° C. to about 1,300° C. in step (3). 
     
     
       3. The method of claim 1, where physical contact is established between the nickel coated fibers after coating and is maintained during the heating step, an additional nickel coating is applied to the fibers after the heating step, the iron-nickel alloy is unmelted and consists essentially of about 60% to 80% iron and about 20% to 40% nickel, the thickness ratio of fiber diameter:nickel coating of step (2) is from about 1:0.02 to 0.25, and the thickness of the outer layer of iron-nickel alloy on the fibers after step (3) is at least 5% of the radius of the fibers. 
     
     
       4. The method of claim 1, where the fibers are heated at a temperature of about 800° C. to 1,300° C. in step (3), an additional nickel coating is applied to the fibers after the heating step, and the fibers are steel fibers. 
     
     
       5. A method of producing a high strength, metallic, electrically conductive battery plaque comprising the steps of: (1) providing a sheet of iron fibers,   (2) deoxidizing said fibers in a non-oxidizing atmosphere,   (3) nickel coating said fibers, and then   (4) establishing physical contact between said nickel coated fibers, and then   (5) maintaining said physical contact between said nickel coated fibers and diffusion bond heating the sheet of nickel coated fibers in a non-oxidizing atmosphere to form an outer layer of iron-nickel alloy on the fibers and to form a diffusion bond of iron-nickel alloy between a substantial amount of the fibers at points of physical contact, to form an electrically conductive plaque of iron-nickel alloy bonded fibers.   
     
     
       6. The method of claim 5, wherein the sheet is heated at a temperature of about 800° C. to about 1,300° C. in step (5), as a last step, an additional nickel strike about 0.000003 inch to about 0.002 inch thick is applied to the fibers, and the fibers are steel fibers. 
     
     
       7. The method of claim 5, wherein the deoxidation in step (2) requires heating at a temperature of about 800° C. to 1,200° C., and between steps (2) and (3), physical contact is established between the uncoated fibers and they are intermediate diffusion bonded in a non-oxidizing atmosphere to form a substantial amount of iron to iron bonding. 
     
     
       8. The method of claim 5, wherein a plurality of nickel plated sheets are provided, the sheets are stacked together and a pressure is imposed upon the stack so that fibers of one sheet are in physical contact with fibers of another sheet and the stack is heated to form said diffusion bonds between fibers. 
     
     
       9. The method of claim 5, wherein the fibers are relatively smooth, free of clefts and protuberances, have a diameter of from about 0.0002 inch to about 0.014 inch and a carbon content of up to about 1%, the electrode plaque is 75 to 95 percent porous, and the nickel coating deposited over the fibers in step (3) has a thickness of from about 0.000003 inch to about 0.002 inch. 
     
     
       10. The method of claim 5, wherein the iron-nickel alloy is unmelted and consists essentially of about 60% to 80% iron and about 20% and 40% nickel, the thickness ratio of fiber diameter:nickel coating of step (3) is from about 1:0.02 to 0.25, and the thickness of the outer layer of iron-nickel alloy on the fibers after step (5) is at least 5% of the radius of the fiber. 
     
     
       11. The method of claim 5, where the thickness of the outer layer of iron-nickel alloy on the fibers after step (5) is from 25% to 100% of the radius of the fiber. 
     
     
       12. The method of claim 5, wherein an electrically conducting metal tab current collector is attached to the plaque. 
     
     
       13. A plaque made by the method of claim 5, including an additional nickel coating applied to the fibers after the heating step, where the plaque is loaded with active battery material. 
     
     
       14. A high strength, electrically conductive battery electrode plaque comprising at least one sheet of contacting iron fibers, a substantial amount of said fibers having iron-nickel alloy bonding the fibers together at fiber contact points, where the iron-nickel alloy consists essentially of about 60% to 80% iron and about 20% to 40% nickel. 
     
     
       15. The battery plaque of claim 14, wherein the plaque is 75 to 95 percent porous, and the fibers are steel fibers having a diameter of from about 0.0002 inch to about 0.014 inch. 
     
     
       16. The battery plaque of claim 14, where the fibers have a carbon content of up to about 1%, the plaque has an outer nickel coating thereon, and the thickness of the iron-nickel alloy on the fibers is at least 5% of the radius of the fibers. 
     
     
       17. The battery plaque of claim 14, where the fibers are randomly oriented, the plaque has an additional nickel coating applied to the bonded fibers, and the electrode is loaded with active battery material and placed in a battery. 
     
     
       18. A plaque made by the method of claim 1, including an additional nickel coating applied to the fibers after the heating step, where the plaque is loaded with active material.